1. Technical Field
The present invention relates to a resonator element and a resonator having the resonator element.
2. Related Art
There is known a resonator element which has a resonating arm and a base portion connected to the resonating arm and in which a tapered portion symmetrical with respect to the vibration center of the resonating arm is provided in a connection portion between the resonating arm and the base portion (for example, refer to JP-A-2005-5896).
In the resonator element disclosed in JP-A-2005-5896, by providing a tapered portion in a connection portion between the resonating arm and the base portion, leakage of fundamental vibration is suppressed, the Q factor is increased accordingly so that a vibration mode is not affected, and it is also possible to prevent the resonator element from being broken by an impact or prevent deterioration of a vibration mode.
In the case where a tapered portion is provided in practice, however, the Q factor is often decreased depending on the shape of the tapered portion. Presumably, this is because a thermoelastic loss resulting from the shape of the tapered portion exceeds an increase in the Q factor resulting from a suppression effect of vibration leakage by providing the tapered portion.